||Rub down test piece with 240 grit wet, trying not to scalp edges too much. Carry on to 600 & 1200 grit wet. Now a lot of ripples visible in the light. Go back to 240 grit and get rid of most of them except a few small dimples, but also going through to the filler all around the edges. Repeat 600 & 1200; feels good but dimples very visible against the light. Go back to rudder and try Gary's suggestion of rubbing it with the bare dry ali channel to leave black witness marks on high spots. One or two areas clearly high, but elsewhere the black is getting deposited quite widely. Not sure what to do now as obviously neither filler nor gel-coat will adhere well to the black aluminium residue. Clean off with acetone, which takes some time to shift it all. Rub again lightly with 180 grit soft spline.
||Phone Martin Carolan and take test piece, rudder and sanding splines to him for comments. He says it all looks OK. Advises against a buildup of filler on the hinge flange, as it will not be as flexible as the underlying layup and so will tend to crack. He shows me a black "pounce" they use for showing up low spots on gel-coat. Suggests that I could use a smaller block for at least some areas, as driving a large one by hand requires a lot of effort. After about 400 grit, could switch to a rubber-faced block which has soft edges so gives less buildup there. Dead flat rigid block not needed with finer grits as they are polishing, not profiling. For filling the rounded areas and small dimples, he says to use less Expancell in the mix so it will stick better and not roll up behind the knife. Yes, it's slightly heavier and slightly harder to sand, but it is much easier to apply. They use a trowel heated on a gas flame for pre-cure levelling of the stiff filler on flattish surfaces. It can be used so hot the resin smokes! Don't rub down between applications of gel-coat as I had been doing - put on another coat as soon as first one has gelled enough to take it. For finishing of the gel-coat, they use something like Webrax in 1000 grit upwards, on a DA sander. It is supplied by a car-body specialist. Using abrasive rather than buffing it is better as the buffing can put in too much heat and this can cause the cloth weave to grin through as the gel-coat reacts to the heat. Order one pack each of the 1000 & 2000 grit sanding pads (Abralon), and the 3M pounce stuff. On way home, buy cheapest iron (5.97) in Currys. All are now steam, can't get a plain one! At home try to take it apart to see where an extension soleplate could be screwed on without hitting the element, but initially thwarted by 2 of the security screws which are more deeply recessed than others. They are Zero-one style, but can be turned with a 5/32" AF, 8BA, or 4mm socket. Look at
Metals on the Web
and request quote for aluminium plate, and ask if I can collect to save carriage on such a small order. Order DA air sander and other bits from
Axminster Power Tool Centre.
||Get small set of 1/4" drive deep sockets from Halfords (3.99), including a 4mm one which is just right for the screws on the iron. However, even with all visible screws undone, I still can't get it apart. I think it must be glued together to maintain steam reservoir integrity. May have to be content with epoxying on big soleplate.
Metals on the Web
quote received and they offer collection from Tewkesbury. Reply saying I'll have a piece of the wide flat bar instead that I hadn't noticed first time around, and which will be slightly cheaper than cutting a piece off a big plate.
||Axminster Power Tool Centre order arrives, but less DA sander. Phone to check and it's been discontinued. They do now have a (cheaper) alternative, so order that.
Metals on the Web
confirms it's OK to collect the piece of flat bar and gives quote ref & Tewkesbury address. Place order for 30cm of 5" x 3/8" on their website.
||DA sander arrives from Axminster Power Tool Centre. Try it out (without any abrasive pads) and it seems OK. As Martin warned, it does consume a lot of air. Circle remaining dimples on rudder with felt-tip pen. Rub them, and tip, with emery paper, and wipe with acetone. Mix 3x batch of slow epoxy. Decant off over half and add about 3 large doses Expancel to only just slumping state. Fill dents and low spots on LE & TE. Paint tip with neat epoxy and trowel on filler with mixing stick. Quite easy to apply and smooths out without any picking up. Erect tent & leave to cure. After some hours, notice filler at tip is dripping off in places.
||Turn off heat (30C, 30%RH). Collect aluminium plate from Tewkesbury. Find some M4 Taptite 8mm screws for attaching it to iron.
Drill edges of iron soleplate
(well clear of element!) through 4mm and up through base & casing. Drill & break off parts of casing to allow screw heads through. Spot holes onto aluminium plate and drill blind holes for Taptite screws. Start with 3.6mm but change to 3.4mm for tighter fit. Countersink top of soleplate holes and fit. Heats up all over quite well. Will need to get some heat-sink compound to improve heat transfer. Take down curing tent. Sand down all filled patches on starboard side of rudder. File and sand tip to shape. Still a few small patches not quite filled. Abrade root with 80 grit sandpaper. Mix 2x batch slow epoxy. Decent off about half and mix with 3 doses Expancel, to slightly drier consistency than yesterday. Paint rudder root with neat epoxy and butter on filler. Erect tent and leave to cure. Later,
filler sagging slightly,
but not dripping off as yesterday.
||Turn off heat.
||Take down curing tent. Abrade rudder port side with 80 grit and wipe over with acetone. Turn on iron with extended soleplate to medium heat. Remove root-end locating batten which was fouling curing tent frame. Mix 10x batch of slow epoxy. Paint rudder with neat epoxy - only need 3 or 4 brushfuls when brushed out as much as possible. Add about a dozen good doses of Expancel to remainder until really dry and non-slump. Spread with filling knife. Goes on much better than first side - I think the mix is very slightly wetter. Just right quantity and enough to go around LE a bit, but that is much harder to get even. Rub over with iron, but it
doesn't actually improve it much.
Best results are with filling knife warmed on soleplate for small areas. Erect tent & leave to cure.
||Turn off heat. Flight medical expiry reminder received from flight medical examiner a few days ago. Today, write to him describing vertigo problems. I've experienced this intermittently since July 2003 and have seen my GP several times and then got referred to an ENT consultant. He diagnosed Benign Paroxysmal Positional Vertigo (BPPV), although he could not excite my symptoms using the standard diagnostic test. He referred me to a physiotherapist for treatment which he assured me was "curative" and to the CAT scanner for a check of my sinuses. The physiotherapist was also unable to excite the symptoms at will. The daily exercises she gave me often brought on slight nystagmus (eye twitches) but didn't seem to affect the occurrence of symptoms through the rest of the day. At the second session, she recommended a gaze stability exercise which triggered no nystagmus, but did make me nauseous and vomit several times for a couple of hours after I did it with more enthusiasm. At the last appointment, she suggested I drop all the exercises and see if it goes away by itself (as it did several times in 2003, and for about 6 weeks in early 2004). Ask medical examiner if I should put off having the medical exam until the problem is resolved.
||AME's secretary phones saying that medical exam should be put off until condition is cleared, and reminding me that I should have told the CAA of my condition.
||Phone CAA flight licensing department to tell them about my BPPV. They confirm that my medical certificate will be suspended until the condition is resolved. The lack of progress with physiotherapy, and the failure of both consultant and physiotherapist to excite my symptoms with the standard Dix-Hallpike test, makes me fear that I've got something more intractable, and that I may not be able to get flight fit again if it can't be sorted out. All this does not make me feel much like doing any aeroplane building.
||Having recovered some faith in the possibility of recovery from the vertigo problem, get back in the garage and take down the curing tent. Take some pictures. Plane the TE support
at a slight angle
to better fit the shape of the rudder. Clean up the inside of the rudder LE vee with various Perma-Grit and other abrasives. Mix 3x batch of slow epoxy. Paint inside of vee with neat epoxy. Add about 4 large doses expancel to the remainder. Spread it into a few scratches still visible on starboard side of rudder, and on LE vee, with filling knife. Smooth bottom of vee with mixing stick as well as possible. Also scrape it off vee faces to leave as thin a coating as possible. Lots of filler left over. Erect tent.
||Turn off heat. Collect heatsink compound ordered last week at Maplin. Phone Ian McGugan to see if he can come round tomorrow to do the final fitting of the trailer underfloor brackets for the gas springs.
||Ian McGugan arrives about 10:30 and we spend most of the morning with me underneath the trailer doing up stiffnuts and getting covered in the underseal I applied to the brackets, and Ian holding a screwdriver inside the trailer. Didn't notice that the ramp brackets had a weld line inside, which fouls my carefully measured spacers, so have to whip them back to the lathe and take another 0.75mm or so off a couple of them. The ones for the other ends of the gas springs are fine, as I'd offered them up while the underfloor brackets were sitting in the garage. Ian has to leave for his IT course, so Wilma holds the big screwdriver bit in the carpenters brace while I do the final tightening of the underfloor nuts. Try to cross-drill the M8 bolts in the ends of the gas-springs for split pins, but after breaking and blunting several drill bits, give up in disgust and put on stiff-nuts instead of the castellated ones I'd intended. The Abralon 1000 and 2000 discs and 3M dry guide coat powder arrive from
Will need to get a velcro type backing pad or adaptor, as my DA sander's pad is for stick-on discs.
||No joy at local car factors or tool places for a velcro backing pad. Take down curing tent, file and sand rudder root to shape. Lots of trapped bubbles emerge - will need a lot more filling. Remove LE location batten. Order velcro backing pad online from
CSM Abrasives Plus.
||Find suitable batten which will butt against rudder LE hinge flange but clearing LE curve and screw it to table, this time making sure that the south end will be clear of the tent frame. Screw on root batten, well towards LE so it is below port surface at TE & won't catch sanding block. Bandsaw a small wedge for supporting tip LE. Take some photos of setup.
Fit rudder into the jig
and rub down port side and LE with large coarse and then fine Perma-Grit blocks. Continue with 80 grit sandpaper and finally 240 grit emery paper on ali channel. A few pinholes appear. Work on LE vee with angled Perma-Grit block, and sandpaper wrapped around foam wedge. Not nearly as good a finish as on outer surfaces, but doesn't feel too bad. Brush out pinholes and degrease with acetone on a toothbrush. Mix 1x slow epoxy and add 5 doses Expancel to non-slump, but still sheening slightly after about half a minute. Spread into all pinholes with mixing stick. Lots left over. Erect curing tent, soon up to 29C, 29%RH. Screw Maplin multi-drawer unit to wall below others.
||Take down curing tent. Sand filled areas using coarse Perma-Grit a little but mostly fine Perma-Grit. Test piece was 180x340mm = 61200 sq mm and took 10 - 20g gel-coat. Rudder is approx 1300x400mm = 520000 sq mm so should take 85 - 170g gel-coat per side - say 100g in round figures so as to be sure of avoiding shortage. Find a clean unused roller tray among the decorating stuff. Vacuum up dust around table and leave filter fan running to keep the air clear. Prop up rudder TE to set port face fairly level. Rub over with acetone-soaked paper towel to degrease & wipe off any remaining dust. Mix 100g + 10g gel-coat. Decide to skip the roller tray and just decant gel-coat straight onto rudder, spreading around well. Roll out with paint roller. Spreads quite well but a lot of woolly hairs left behind. Seems to be starting to gel almost as soon as I've rolled it out. Clean roller with acetone. Leave for about 20 or 30 minutes. Mix 120g + 12g gel-coat and spread as for first coat. Even more hairs deposited this time - I thought they would diminish after first use and wash of roller. Repeat all again with 3rd coat. Send e-mail to Martin Carolan about roller problems. Reply received later saying their rollers come from somewhere near Bristol. I'll think about that for the larger parts, but for now I'll go back to brushes.
||Take photos of
Apply dry guide coat (with some difficulty because of stiff hairy excresences). There's also an "orange-peel" effect over most of the surface, which takes a lot more work to remove than the hairs. Filler and glass layer starts to appear in a few patches before all the dimples are gone. Rinse off and dry to check appearance a few times as work progresses. Take sanding over onto LE a bit too. When finally satisfied with removal of dimples, rub over with 600 emery on rubber block to remove last of dry guide coat. Wash off, dry & wipe down with acetone-soaked paper towel. Take photos. Find good 1.5" paintbrush. Start to mix 200g + 20g gel-coat before remembering that scale only reads to 200g! Split it into 2 cups and combine after initial stirring. Pour onto rudder, spreading all over. Brush out to edges, making sure of good coverage at areas of exposed filler/glass. 220g is really too much, as it's still tending to pool in places after the edges are well covered. Signs of starting to gel, so stop brushing out. Take photos.
||Velcro backing pad for DA sander arrives from CSM Abrasives Plus
. Abralon disc fits nicely on it.
||Get 3/8" hose barb to male PCL adaptor at Machine Mart. Make up hose tail with lubricator and fit to DA sander. Remove nibs and runs of gel-coat on starboard side of rudder to allow it to lie flat. Re-position in sanding fixture (need to remove & re-fit root batten to get it in this time). Apply dry guide coat. Rub down with 240 emery wet. Start with small ali bar but switch to channel as more comfortable. Eventually get rid of all visible low spots. Emery disintegrating along edges of channel so round off edges with file and emery cloth. Clean off and dry rudder, apply fresh guide coat. Start to rub with 600 emery wet and several low spots appear again! Clean off and return to 240 grit. Thin patches now becoming visible at tip, LE, TE and around CS29 rivets. Guide coat again and switch to 600 grit. Still low patches appear but less marked than before, and they can be cleared with a bit of effort. I know I'll have to repeat it all again because of the thin patches but can't resist going on to 1200 grit emery and 2000 grit Abralon (both hand held) just to see what the finish will look like. Also rub on some Farecla G3 to make it a bit glossy (tried G10 first but it was too fine to be effective at this stage). Generally very
pleased with the effect
and the overall appearance.
||Phone Martin Carolan to check what sanding need to key new gel-coat. He says 400 grit, and if doing patches, roughen and re-coat a good margin all around the area where extra coverage is needed. Search locally without success for rubber sheet to make a softer sanding block with, for the finer grades. Find a piece of leftover thick floor vinyl instead. Cut off a length of 3"x1.5" aluminium channel and round edges and corners with file and emery cloth. Scuff-sand both vinyl & ali, degrease with meths and stick together with contact adhesive. Clamp together in vise with other piece of ali for a few minutes to ensure good contact throughout. With new blade in Stanley knife, trim off excess vinyl, chamfering at about 45 degrees all round. No 400 grit in stock, but have some 360 grit. Wet rudder port side and lubricate emery with washing-up liquid. Scuff all over port face and around onto LE, root, and tip. Rinse off and dry, check no un-sanded areas left. Wipe over with acetone-soaked tissue. Mix 100g + 10g gel-coat and pour on. Spread with brush. Seems adequate quantity - the roller must have been soaking up a lot of it, as this much barely covered the whole side when rolled on. Remove one dead insect before leaving - first time that's happened, must have been lucky before. To ensure it's well gelled and eliminate danger of pick-up, leave to cure for about 90 minutes (longer than last time, and longer than really intended - watching last episode of Friends!) before doing next coat. Mix 100g + 10g gel-coat, pour on and brush out.
||Sand off nibs and runs on starboard side of rudder. Unscrew root batten and replace to re-clamp rudder. Apply dry guide coat. Re-fit 240 emery to fresh place on ali channel. Lubricate with washing-up liquid and water, and
rub down port side
of rudder. Tip & TE are OK, but tiny thin patches starting to appear again at CS29 rivet and on LE. Also 2 pinholes or bubbles have appeared, which look too deep to remove. Maybe I can put a dot of gel-coat on each when doing next area. When all low spots gone, rinse and dry off and re-apply guide coat. Start rubbing with 360 emery wet on ali channel and several low spots re-appear. Keep going and they all eventually go. Stop and think what to do next. Probably good to leave this side at the 360 stage and gel-coat rest of it before moving on to finer grades. If I do the LE vee and/or root and tip next, I will be able to get at the pinholes and the CS29 rivet area for touch-ups.